The present invention relates to the field of nucleoside compounds and nucleoside analog compounds.
A nucleoside comprises two parts: a) a heterocyclic nitrogenous base portion, termed a purine or pyrimidine; and b) a sugar portion. Nucleoside analogs are compounds that are similar in structure and composition to nucleosides, but one or more of the substituents differ from naturally occurring nucleosides.
Ribavirin (1-xcex2-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a nucleoside analog that has demonstrated efficacy in treating viral diseases both as monotherapy (respiratory syncytial virus, Hall, C. B.; McBride, J. T.; Walsh, E. E.; Bell, D. M.; Gala, C. L.; Hildreth, S.; Ten Eyck, L. G.; W. J. Hall. Aerosolized ribavirin treatment of infants with respiratory syncytial viral infection. N. Engl. J Med. 1983, 308, 1443-1447), and in combination therapy with interferon-alpha (hepatitis C virus, Reichard, O.; Norkrans, G.; Fryden, A.; Braconier, J-H.; Sonnerborg, A.; Weiland, O. Randomized, double blind, placebo controlled trial of interferon alpha 2B with and without ribavirin for chronic hepatitis C. Lancet 1998, 351, 83-87). Recently reported studies indicate that the in vivo utility of ribavirin can result not only from direct inhibition of viral replication, but also from its ability to enhance T cell-mediated immunity (Hultgren, C.; Milich, D. R.; Weiland, O.; Sallberg, M. The antiviral compound ribavirin modulates the T helper Type1/Type2 subset balance in hepatitis B and C virus-specific immune responses. J. Gen. Virol. 1998, 79, 2381-2391; Ning, Q.; Brown, D.; Parodo, J.; Cattral, M.; Fung, L.; Gorczynski, R.; Cole, E., Fung, L.; Ding, J. W.; Liu, M. F.; Rotstein, O.; Phillips, M. J.; Levy, G. ribavirin inhibits viral-induced macrophage production of tumor necrosis factor, interleukin-1, procoagulant activity fg12 prothronibinase and preserves Th1 cytokine production but inhibits Th2 cytokine response. J. Immunol. 1998, 160, 3487-3493; Martin, M. J.; Navas, S.; Quiroga, J. A.; Pardo, M.; Carreno, V. Effects of the ribavirin-interferon alpha combination on cultured peripheral blood mononuclear cells from chronic hepatitis C patients. Cytokine 1998, 79, 2381-2391. This immunomodulatory effect of ribavirin is demonstrable in vitro by measuring the levels of Type 1 cytokines produced by activated T cells from both humans and mice (Tam, R. C.; Pai, B.; Bard, J.; Lim, C.; Averett, D. R.; Phan, U. T.; Milovanovic, T. ribavirin polarizes human T cell responses towards a Type 1 cytokine profile. J. Hepatol. 1999, 30, 376-382), and by other measures. The induction of a Type 1 cytokine bias by ribavirin is functionally significant in vivo in murine systems (Tam, R. C.; Lim, C.; Bard, J.; Pai, B. Contact hypersensitivity responses following ribavirin treatment in viva are influenced by Type 1 cytokine polarization, regulation of IL-10 expression and costimulatory signaling. J. Immunol. 1999, 163, 3709-3717).
Mammalian immune systems contain two major classes of lymphocytes: B lymphocytes (B cells), which originate in the bone marrow; and T lymphocytes (T cells) that originate in the thymus. B cells are largely responsible for humoral immunity (i.e., antibody production), while T cells are largely responsible for cell-mediated immunity.
T cells are generally considered to fall into two subclasses, helper T cells and cytotoxic T cells. Helper T cells activate other lymphocytes, including B cells and cytotoxic T cells, and macrophages, by releasing soluble protein mediators called cytokines that are involved in cell-mediated immunity. As used herein, lymphokines are a subset of cytokines.
Helper T cells are also generally considered to fall into two subclasses, Type 1 and Type 2. Type 1 cells produce interleukin 2 (IL-2), tumor necrosis factor (TNFxcex1) and interferon gamma (IFNxcex3), and are responsible primarily for cell-mediated immunity such as delayed type hypersensitivity and antiviral immunity. In contrast, Type 2 cells produce interleukins, IL4, IL5, IL-6, IL-9, IL-10 and IL-13, and are primarily involved in assisting humoral immune responses such as those seen in response to allergens, e.g. IgE and IgG4 antibody isotype switching (Mosmann, 1989, Annu Rev Immunol. 7:145-173).
As used herein, the terms Type 1 and Type 2 xe2x80x9cresponsesxe2x80x9d are meant to include the entire range of effects resulting from induction of Type 1 and Type 2 lymphocytes, respectively. Among other things, such responses include variation in production of the corresponding cytokines through transcription, translation, secretion, and possibly other mechanisms, increased proliferation of the corresponding lymphocytes, and other effects associated with increased production of cytokines, including motility effects.
Previous applications (e.g., 09/291903, now U.S. Pat. No. 6,130,326) which is incorporated herein by reference, relates to aspects of our recent discoveries involving the effect of various nucleosides (which are defined herein to include derivatives and analogs of native nucleosides) on selectively modulating lymphocyte responses relative to each other. Among other things, we have shown that either of Type 1 and Type 2 responses can be selectively suppressed while the other is either induced or left relatively unaffected, and either of Type 1 or Type 2 responses can be selectively induced while the other is either suppressed or left relatively unaffected. We have also discovered the surprising fact that some nucleosides effective in selectively modulating Type 1 and Type 2 responses relative to one another tend to have a bimodal effect. Among other things, some nucleosides that tend to generally suppress or induce both Type 1 and Type 2 activity at a relatively higher dose tend to selectively modulate Type 1 and Type 2 relative to each other at relatively lower doses.
Viramidine (1-xcex2-D-ribofuranosyl-1,2,4-triazole-3-carboxamidine hydrochloride) has been shown active in ten different viruses that are comparable to ribavirin. (J. T. Witkowski, R. K. Robins, G. P. Khare, R. W. Sidwell, J. Med. Chem., 16, 935-937, 1973; R. W. Sidwell, J. H. Huffman, D. L. Barnard, D. Y. Pifat, Antiviral Research, 10, 193-208, 1988; B. Gabrielsen, M. J. Phelan, L. Barthel-Rosa, C. See, J. W. Huggins, D. F. Kefauver, T. P. Monath, M. A. Ussery, G.
N. Chmurny, E. M. Schubert, K. Upadhya, C. Kwong, D. A. Carter, J. A. Secrist III, J. J. Kirsi, W. M. Shannon, R. W. Sidwell, G. D. Kini, R. K. Robins, J. Med. Chem., 35, 3231-3238, 1992). In addition, Viramidine(trademark), like ribavirin, is an inhibitor of IMP dehydrogenase (R. C. Willis, R. K. Robins, J. E. Seegmiller, Molecular Pharmacology, 18, 287-295, 1980). Furthermore, preliminary toxicology studies suggest that Viramidine(trademark) is less toxic than ribavirin (D. Y. Pifat, R. W. Sidwell, P. G. Canonico, Antiviral Research, 9, 136, 1988). Also, recent studies at our lab (R. Tam, K. Ramasaniy, ICN Pharmaceuticals, Inc., unpublished results, 1999) revealed that Viramidine(trademark) and ribavirin exhibited similar immunomodulatory properties. These results coupled with low bioavailability and the toxicity associated with ribavirin prompt us not only to develop Viramidine(trademark) for other viral diseases but also to prepare other derivatives of viramidine, including the synthesis of prodrugs of viramidine, and screen them as potential antiviral agents.
Ribavirin and Levovirin(trademark) are similar with respect to structure, except that Levovirin(trademark) is the L-configuration of the compound and has a substantially reduced toxicity. For example, while oral administration of ribavirin in rats at 180 mg/kg over four weeks produced significant hemolytic anemia and leukopenia, Levovirin(trademark) did not produce any observable clinical pathology. Furthermore, it is contemplated that treatment of a viral disease with Levovirin(trademark) is predominantly based on the modulation of the Th1/Th2 balance towards a Th1 dominated response, and not predominantly based an a direct antiviral effect. The term xe2x80x9cdirect antiviralxe2x80x9d effect or activity as used herein refers to an immediate effect or activity of a drug on viral assembly or replication. In contrast, a reduction of viral activity or replication that is at least in part mediated by one or more components of the immune system is not considered a xe2x80x9cdirect antiviralxe2x80x9d effect or activity. Likewise, it should be appreciated that a relative reduction of the Th2 response during a treatment may be especially advantageous in diseases that are correlated with an increased Th2 response (e.g., HCV infection).
The effect of other nucleoside analog compounds on selectively modulating lymphocyte responses relative to each other has not been previously studied or documented. We have discovered that the bimodal effect, or selective modulation of Type 1 and Type 2 responses relative to one another, also occurs after administration of other nucleoside analog compounds, such as pro-drug forms of the compounds.
There are many barriers to overcome in developing biologically active compounds into clinically useful agents. Many potent biologically active compounds never become clinically useful agents because of their undesirable biopharmaceutical properties which include low bioavailability due to low permeability through biological barriers, such as the blood brain barrier (BBB) and the intestinal barrier. Although many factors affect the bioavailability of a drug, the undesirable physicochemical properties (e.g., charge, lipophilicity, hydrogen bonding potential, size) of many drugs is probably one of the most commonly encountered factors that hinder the permeation of drugs through biological barriers. Therefore, optimization of the physicochemical characteristics (charge, lipophilicity, hydrogen bonding potential, size) of a drug is probably the most likely general strategy to facilitate the transport of drugs through such membrane barriers.
To optimize the physicochemical properties of drugs, one possible strategy is that of prodrugs. (H. Bundgaard, Design of Prodrugs, Elsevier, Amsterdam, 1985; N. Bodor, L. Prokai, W. M. Wu, H. Farag, S. Jonalagadda, M. Kawamura, J. Simpkins, Science, 257, 1698-1700, 1992; H. E. Taylor, K. B. Sloan, J. Pharm. Sci, 87, 5-20, 1998). The term prodrug is used to describe an agent, which must undergo chemical or enzymatic transformation to the active or parent drug after administration, so that the metabolic product or parent drug can subsequently exhibit the desired pharmacological response. By derivatizing certain polar functional groups in small organic molecules transiently and bioreversibly, the undesirable physicochemical characteristics (e.g., charge, hydrogen bonding potential) of these groups have been xe2x80x9cmaskedxe2x80x9d without permanently altering the pharmacological properties of the molecules. This strategy has been very successfully used in cases where the prodrug derivatization involves converting a carboxyl or a hydroxyl functional group into an ester, which can be readily hydrolyzed in vivo either chemically, or enzymatically. The promising prodrug concept, we anticipate that the introduction of other moieties in the parent drug would increase the bioavailability, adsorption, and antiviral effects.
Despite the existence of as-yet undefined mechanisms, we have discovered that enormous potential benefits can be derived from selective modulation of Type 1 and Type 2 responses relative to each other. We have concluded, for example, that specific modulation of Type 1 relative to Type 2 can be useful in treating a wide variety of conditions and diseases, ranging from infections, infestations, tumors and hypersensitivities to autoimmune diseases.
These discoveries are especially significant because modem treatment strategies for many of the above-listed diseases have limited effectiveness, significant side effects, or both. Treatment of autoimmune disease, for example, is frequently limited to palliative measures, removal of toxic antibodies (as in myasthenia gravis), and administration of hazardous drugs including corticosteroids, chloroquine derivatives, and antimetabolic or antitumor drugs, and drugs such as cyclosporines that target immune system cells.
The present invention is directed to novel nucleoside analog compounds and related compounds, such as prodrugs, their therapeutic uses and synthesis.
In one aspect of the invention, there are provided nucleosides, nucleoside analog compounds and nucleoside prodrugs of the generalized Formula 1, in which the sugar is either in the L-or D-conformation:
Rxe2x80x94Nu
where Nu is a nucleoside or nucleoside analog compound; and R, which may or may not be present, comprises a ligand, otherwise termed a substituent, that is designed to modify the nucleoside through modification of the sugar, the base, or in some cases both the sugar and the base.
In one aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 1, in which the sugar is either in the L- or D-conformation: 
wherein: A, C and D are independently selected from N or Cxe2x80x94R9; R9 is independently H, halogens, lower alkyl, alkenyl, alkynyl, amino, CN, SH, CHO, COOH, CH2OH, vinyl halide or hydroxyl; Z is independently selected from O, CH2 or S; R is independently selected from H, hydroxyl, protected hydroxyl or halogens; R1, R2, R3, R4, R5, are independently selected from H, halogens, CN, CH2OH, lower alkyl, vinyl or acetylene; when R2 is hydroxyl, then, R that is attached to the same carbon as that of R2 is not halogen; when R3 is hydroxyl, then, R that is attached to the same carbon as that of R3 is not halogen; R6 is independently selected from H, hydroxyl, protected hydroxyl, xe2x80x94CH2OH, xe2x80x94CH2PO(OH)2xe2x80x94, O-amino acids, O-retinoic acid, O-cholesteral, O-cholic acid, O-coumarinic acid, O-salicylic acid, O-succinic acid, O-bile acid, O-lipids, Oxe2x80x94P(O)xe2x80x94(Oxe2x80x94CH2xe2x80x94CH2xe2x80x94Sxe2x80x94COxe2x80x94CH3)2; O-steroids; O-monophosphate derivatives, O-diphosphate derivatives or O-triphosphate derivatives; R7 is independently selected from H, alkyl, CH3COOxe2x80x94, CH3COO-Phenyl-CH2xe2x80x94Oxe2x80x94COxe2x80x94, phenyl, xe2x80x94(CH2)nxe2x80x94COOH, coumarinic acid, salicylic acid, dithiosuccinoyl derivatives, reductase mediated cleavable groups, phosphonoformic acid or phosphoramidates groups; R8 is independently selected from H, HHCl, HHBr, lower alkyl, phenyl, CH3COOxe2x80x94, CH3COO-Phenyl-CH2xe2x80x94Oxe2x80x94COxe2x80x94, phenyl, or xe2x80x94(CH2)nxe2x80x94COOH; R7 and R8 combined are selected from cyclic structure or amino acids.
In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 3, in which the sugar is either in the L- or D-conformation: 
wherein X is O or NH; R1 is a masking group of the amino group; R2 is selected from H, HCOxe2x80x94, Rxe2x80x94C(O)xe2x80x94, and (Rxe2x80x2O)2P(O)xe2x80x94Oxe2x80x94, where R is C1-C17 alkyl alkenyl, or alkynyl group and Rxe2x80x2 is a masking group of the phosphate; R3 is independently H or C1-C18 acyl; R1 and R2 are not hydrogen at the same time.
In another aspect of the invention, there are provided nucleoside analog Compounds and prodrugs of Formula 4, in which the sugar is either in the L- or D-conformation: 
where R is a masking group having any of the following structures: 
where X is O or S; R is C1-C18 alkyl, alkenyl, alkynyl, aryl, and aralkyl, straight or branched.
In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 5, in which the sugar is either in the L- or D-conformation: 
where R1 is H or a masking group as designated in claim 2; R2 is a masking group of the phosphate having any of the following structures: 
where X is O, or S; Ris C1-C18 alkyl, alkenyl, alkynyl, aryl, aralkyl straight or branched; Rxe2x80x2, Rxe2x80x3 are selected from H, alkyl, aryl but Rxe2x80x2 and Rxe2x80x3 are not hydrogen at the same time.
In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 6, in which the sugar is either in the L- or D-conformation: 
where R1 is H or a masking group as designated in claim 2; R2 is a masking group of the phosphate having any of the following structures: 
where R is C1-C18 alkyl, alkenyl, alkynyl, aryl, and aralkyl, straight or branched;
M is selected from alkyl, alkenyl, alkynyl, aralkyl, aryl, and a group of hydrophobic compounds such as cholesterol, vitamin D derivative, and cholic acid derivatives bearing a linker which can be covalently attached to the carbonyl group.
In yet another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 7: 
In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 8: 
In yet another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 9: 
In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 10: 
wherein: R is independently selected from hydrogen, halogens, amide, amidines, alkyl, phenyls, vinyl, or acetylene;
In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 11: 
wherein: X is independently selected from oxygen, sulphur, Se or NR; R is independently selected from hydrogen, acetyl or alkyl; In another aspect of the invention, there are provided nucleoside analog compounds and prodrugs of Formula 12: 
In yet another aspect of the invention, a pharmaceutical composition comprises a therapeutically effective amount of any one or a combination of Formulas 1-12, or a pharmaceutically acceptable ester or salt thereof admixed with at least one pharmaceutically acceptable carrier.
In yet another aspect of the invention, a pharmaceutical composition comprises a pro-drug form of any one or a combination of Formulas 1-12, or a pharmaceutically acceptable ester or salt thereof admixed with at least one pharmaceutically acceptable carrier.
In a further aspect of the invention, a compound according to any one of Formulas 1-12 are used in the treatment of any condition which responds positively to administration of the compound, and according to any formulation and protocol which achieves the positive response. Among other things, it is contemplated that compounds of Formulas 1-12 may be used to treat an infection, an infestation, a cancer, tumor or other neoplasm, giant cell arteritis, or an autoimmune disease.